Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int main()
{
    int H, W; cin>>H>>W;
    vector<string> s(H);
    for(auto& v: s) cin>>v;

    int res=-1;
    queue<tuple<int, int, int>> q;
    q.emplace(0, 0, 1);
    while (q.size()) {
        int r, c, k;
        tie(r, c, k)=q.front();
        q.pop();
        if (r==H-1 && c==W-1) {
            res=-k;
            break;
        }
        array<int, 4> dr={-1, 0, 1, 0};
        array<int, 4> dc={0, -1, 0, 1};
        for(int i=0; i<4; ++i) {
            int nr=r+dr[i], nc=c+dc[i];
            if (nr<0 or nr>=H or nc<0 or nc>=W) continue;
            if (s[nr][nc]!='.') continue;
            q.emplace(nr, nc, k+1);
            s[nr][nc]=' ';
        }
    }

    if (s[H-1][W-1]!='.')
        for(auto& v: s) for(auto& e: v) res+=e!='#';
    cout<<res<<endl;
}